Biologic characteristics of an immunosuppressive factor derived from a human lung cancer cell line

Effect of immunosuppressive factor produced by human lung cancer cell line A549 on the production and action of interleukin 1

A549, a human lung cancer cell line, spontaneously produces a tumor-derived immunosuppressive factor (TDSF) which inhibits the production and action of interleukin 1 (IL-1). After exposure of macrophages to TDSF for 5 h, the production of IL-1 by macrophages was significantly inhibited. The inhibition was much stronger if TDSF existed continuously in macrophage culture. The response of thymocytes treated with nylon wool to exogenous IL-1 was significantly suppressed in the presence of TDSF, suggesting that TDSF can inhibit the action of IL-1. The thymocytes untreated with nylon wool could proliferate after being stimulated with Con A. The proliferation was significantly suppressed by TDSF in a dose-dependent manner. These results suggest that the inhibitory action of TDSF on T cell activation is associated with IL-1, and that TDSF might exert an inhibitory action on other reactions mediated by IL-1. Furthermore, TDSF can reduce the supplementation of new T cells by inhibiting the proliferation of thymocytes.